Wireless telecommunications systems which comprise one central node which communicates with a number of subscribers or terminals are known.
The uplink, i.e. the connection from the terminals to the central node, is usually limited by interference between transmissions from the terminals. Different so called access schemes, such as e.g. TDMA, FDMA and CDMA, (Time/Frequency/Code Division Multiple Access) utilize different ways of separating subscribers within the allowed frequency spectrum in order to limit interference.
As a first example, in a TDMA (Time Division Multiple Access) scheme, the terminals are usually only allowed to transmit one at a time, in order to minimize interference. As a second example, in a CDMA (Code Division Multiple Access) scheme, the terminals are usually only allowed to transmit with unique spreading codes. In these and in other access schemes, one result is an upper limit on the capacity for transmission.
In systems of the kind described above, i.e. a wireless telecommunications systems with one central node which communicates with a number of subscribers or terminals, there is thus a need for a solution or a system by means of which the transmission capacity on the uplink can be increased.
This need is addressed by the present invention in that it discloses a wireless telecommunications system for stationary or semi-stationary equipment. The system comprises a main node, and a first plurality of terminals which belong to the same access subset and which are arranged to receive from and transmit to the main node (C).
The main node transmits in at least one antenna beam and receives in at least two antenna beams, and the system comprises means for indicating to terminals that they may or may not transmit to the central node.
Based upon certain criteria, two or more terminals located in different receive beams of the main node may be given permission to transmit to the central node simultaneously.
Suitably, two or more terminals which are given permission to transmit simultaneously do so using the same frequency or the same spreading code, or during the same time slot.